I have a Coleman EB15B series furnace. When the heat cycle is activated and the air starts blowing two of the closest registers put out hot air but the rest only put out lukewarm air, I have been under the house and have found no holes in the duct work. Is it possible that one of the heating elements is burned out? There is a 9.6kw and a 4.8kw on the furnace.

The elements are located in the unit so the heat output will be the same. Sometimes the heat at a closer register will be a bit hotter than the register farther away. You will need to test the heaters to be sure they are both working. I would use a Amprobe for that and a thermometer to test the temperatures.